package com.example.ch_71;

enum CommandState {
    IDLE,
    DO,
    UNDO,
}

// Command 抽象类
public abstract class AbsCommand {
    protected CommandState state;

    public AbsCommand() {
        this.state = CommandState.IDLE;
    }

    public int execute(int value) {
        return 0;  
    }
    public int undo() {
        return 0;
    }
}
